The bacterial flora of the Oberea linearis (Coleoptera: Cerambycidae) was investigated and 13 different bacteria were isolated from O. linearis larvae. Seven of these bacteria were performed and characterized at species level and the rest of them were characterized at genus level. In this study, we determined morphological and physiological characteristics of the bacterial isolates by conventional and routine techniques, biochemical properties and metabolic enzyme profiles by API20E and Phoenix 1000A panel test systems. Additionally, 16S rRNA gene sequence analysis was also performed to identify the isolates at the molecular level. The isolates were identified as Acinetobacter calcoaceticus (Ol1), Enterobacter aerogenes (Ol2), Pseudomonas sp. (Ol3), Flavobacterium sp. (Ol4), Microbacterium sp. (Ol5), Enterobacter agglomerans (Ol6), Xanthomonas sp. (Ol7), Pseudomonas syringae (Ol8), Pseudomonas sp. (Ol9), Xanthomonas sp. (Ol10), Enterobacter cancerogenus (Ol11), Xanthomonas maltophilia (Ol12), and Serratia marcescens (Ol13). This is the first record of bacterial isolates (Ol5, Ol8, Ol11, Ol12) from any insect. All these bacteria were tested against O. linearis larvae, and Serratia marcescens was found to cause the highest mortality (65%). On the other hand, we determined 90% mortality against this pest within four days by utilizing spore and crystal mixture of Bacillus thuringiensis isolated from Melolontha melolontha.